Panel support construction accessories come in a variety of different configurations, shapes and sizes, and serve a variety of different functions in exterior construction applications. Panel support construction accessories generally include a plurality of flanges obliquely extending relative to one another to form a channel sized to receive a construction panel. Panel support construction accessories have various uses, such as supporting panels, supporting coatings of construction fluid materials adjacent the panels, producing durable straight lines, smooth curves and arches, providing soffit ventilation, controlling expansion and contraction and protecting corners and edges. Panel support construction assemblies further protect and preserve edges of construction panels, such as wallboard, sheathing, and insulation boards from impact and condensation. Panel support construction accessories are commonly known by various names, including but not limited to, corner beads, casing beads, starter strip/casing beads, reinforced, drip casing beads, controlled joints and soffit vents. Panel support construction accessories are used in exterior finishing systems known as direct exterior finishing systems (DEFS) and exterior insulated finishing systems (EIFS).
Panel support construction accessories are typically supported adjacent a support structure lined with a moisture barrier. After a construction panel is inserted into the channel of the panel support construction accessory, the front of the accessory as well as the front of the construction panel are typically coated with a polymer based or polymer modified exterior construction fluid material, such as stucco, cement matrix material or gypsum matrix materials, including acrylic modifiers, or are lined with a preformed sheet of weatherproof material. As a result, the panel support construction accessory, moisture barrier and the outer coating, or sheet of weatherproof material, form an enclosure partially surrounding and encasing the construction panel. In addition to encasing the construction panel, the enclosure traps moisture adjacent to the construction panel. Unless perfectly sealed, additional moisture may enter the system through various cracks or openings. Moisture trapped within the enclosure and condenses to damage the construction panel. In addition, trapped moisture may change state from a liquid to a solid (ice) and expand in volume. This change in volume further damages the enclosure by causing the coating to crack or by causing deformation of the panel support construction accessory. As a result, it is critical that moisture within the enclosure be allowed to escape. At the same time, however, it is also critical that any methods used to vent moisture from the enclosure not enable wind-blown moisture to re-enter the enclosure or allow insects, such as flying termites, to enter the enclosure.